In the petroleum industry, it is common for light gas oils, particularly middle distillate petroleum fuels, to contain sulfur species. Engines and vehicles utilizing these contaminated fuels can produce emissions of nitrogen oxide, sulfur oxide and particulate matter. Government regulations have become more stringent in recent years with regard to allowable levels of these potentially harmful emissions.
Various methods have been proposed to reduce sulfur levels in these light gas oils. However, there are disadvantages associated with these previously proposed methods. For example, hydrodesulfurization of fuel in catalytic reactors has been proposed, whereby the catalyst can remove thiophenic, benzothiophenic and dibenzothiophenic sulfur compounds from the fuel. However, effective hydrodesulfurization of petroleum fuel streams by catalyst often requires the use of two or more reactors in series under low flow rate and high temperature, pressure and hydrogen consumption conditions. These severe operating conditions are necessary to overcome strong inhibition by refractory sulfur and nitrogen compounds against hydrodesulfurization.
Various organic and inorganic adsorbents have also been proposed to effectuate adsorptive removal of sulfur compounds. Examples of previously proposed adsorbents include silica, alumina, zeolite, activated carbon, activated carbon-based fiber materials and spent hydrodesulfurization catalyst. However, the volumetric adsorption capacity for these adsorbents was often too low, and breakthrough of sulfur compounds into the fuel product was often too rapid. Also, inorganic adsorbents typically require high temperature treatment for regeneration, which is not practical for stable and continuous operation, and the adsorption regeneration cycle is too frequent, which makes efficient operation difficult. Further, these adsorbents are often expensive and susceptible to attrition. Fine particles produced due to attrition between adsorbent particles cause plugging and high pressure drop, which can shorten the run length of an adsorption process.
It would be beneficial to have a composition and process for removing sulfur compounds from middle distillate petroleum fuels that exhibits high selectivity at ambient temperature and high volumetric adsorption capacity upon thermal treatment. It would also be beneficial to have a composition and process for removing sulfur compounds from middle distillate petroleum fuels that demonstrates high attrition strength and longer adsorption bed lifespan. It would also be beneficial to have a composition and process for removing sulfur compounds from middle distillate petroleum fuels that can be regenerated using common solvent, and does not require special activation treatment prior to reuse.